DOI: https://doi.org/10.21203/rs.2.344/v4
Fentanyl is used widely for general anesthesia induction due to its rapid onset, intensive analgesia and cardiovascular stability; however, an irritating cough may be caused after its intravenous (IV) administration [1]. The incidence of fentanyl-induced cough (FIC) can reach 80% [2]. The FIC may be transitory and limited; however, it can be explosive and detrimental especially in patients with increased intracranial, intraocular, intrathoracic, or intra-abdominal pressure [3-5]. FIC could even cause severe upper airway obstruction and aspiration pneumonia that require immediate intervention [6, 7]. A report that explosive FIC produced multiple conjunctival and periorbital petechiae has been published [8]. FIC needs immediate and effective intervention especially in patients with cerebral aneurysm, brain trauma, hernia, open eye injury, dissecting aortic aneurysm, pneumothorax or hypersensitive airway disease. Precaution of FIC in these situations is of great importance.
The mechanism of FIC has not been elucidated definitely, although various studies have been conducted to suppress or alleviate this side effect [4, 9]. A previous study has shown that intravenous clonidine could suppress FIC effectively through its α2-adrenoceptor agonist effect [10]. Dexmedetomidine, a highly selective α2-adrenoceptor agonist, is widely used for its particular virtues, such as favorable sedative and analgesic effects. It can also reduce central sympathetic outflow and stress response [11]. A previous study has shown the suppressing effect of dexmedetomidine combined with midazolam on FIC [12]. While another study reported that better cough suppression was found at 1 mcg/kg vs. 0.5 mcg/kg dexmedetomidine bolus without an increase in side effects [13]. However, we should be concerned about its antisympathetic responses with higher doses of dexmedetomidine. Therefore, we designed a study to investigate the optimal priming dose of dexmedetomidine in FIC suppression during general anesthesia induction.
Parameters
Group 1
Group 2
Group 3
Group 4
Age (years)
46.8±14.3
49.9±11.8
47.3±13.4
45.3±10.0
Gender (males/females)
19/23
20/22
18/24
21/21
Weight (kg)
68.6±11.8
69.8±10.6
65.7±12.6
63.4±9.8
BMI (kg/cm2)
24.5±2.8
25.1±3.2
24.2±3.6
23.0±2.3
ASA (I/II)
24/18
26/16
26/16
25/17
Table 1. Demographic characteristics of patients in the four groups.
Values are mean ± standard deviation.
Cough
Group 1
Group 2
Group 3ac
Group 4ac
Onset time (s, x ± s)
11.8±4.5
17.5±6.5b
17.4±5.7b
17.2±5.8b
Incidence (n, %)
22 (52.4)
18 (42.9)
5 (11.9)
6 (14.3)
Severity
(n, %)
0 (No cough)
20 (47.6)
24 (57.1)
37 (88.1)
36 (85.7)
1 (Mild)
8 (19.0)
8 (19.0)
3 (7.1)
5 (11.9)
2 (Moderate)
8 (19.0)
6 (14.3)
1 (2.4)
1 (2.4)
3 (Severe)
6 (14.3)
4 (9.5)
1 (2.4)
0 (0)
Table 2. Onset time, incidence and severity of cough in the four groups.
Onset time: from the end of fentanyl injection to the beginning of coughing.
a P < 0.01, b P < 0.05 compared to group 1, c P < 0.05 compared to group 2.
Figure 1. Consolidated Standards of Reporting Trials (CONSORT) recommended description of patient recruitment
Figure 2. Effects of pretreatments on HR in the four groups.
HR: heart rate; bpm: beats/min.
T0: at the beginning of pretreatment; T1: 3 min after the beginning of pretreatment; T2: 6 min after the beginning of pretreatment; T3: 9 min after the beginning of pretreatment; T4: 12 min after the beginning of pretreatment.
a P < 0.05, b P < 0.01, compared to T0.
Figure 3. Effects of pretreatments on MAP in the four groups.
MAP: mean arterial pressure.
T0: at the beginning of pretreatment; T1: 3 min after the beginning of pretreatment; T2: 6 min after the beginning of pretreatment; T3: 9 min after the beginning of pretreatment; T4: 12 min after the beginning of pretreatment.
a P < 0.05, compared to T0.